Guide
The coating is part of the design
Nickel-copper-nickel, epoxy, parylene, zinc, phosphate, e-coat, and encapsulated assemblies each solve different problems. A small sensor magnet in a dry enclosure, an outdoor latch assembly, and a motor magnet exposed to heat and oil should not default to the same coating.
Failure modes to avoid
Coating damage can start during handling, magnet-to-magnet impact, adhesive bonding, press-fit assembly, or thermal cycling. Once moisture reaches the alloy, corrosion can reduce magnetic output, swell the part, break plating, and create dimensional or cleanliness issues.
Validation inputs
Salt spray, humidity, thermal cycling, coating adhesion, chemical exposure, and assembly pull tests should be selected around the actual use case. For high-volume programs, include inspection points for coating thickness, chips, cracks, exposed edges, and post-assembly magnetic performance.